U.S. patent application number 10/732454 was filed with the patent office on 2004-06-24 for apparatus and method for adjusting optical pickup.
This patent application is currently assigned to Pioneer Corporation. Invention is credited to Miyata, Yasuhisa, Nakahashi, Masahiro.
Application Number | 20040120230 10/732454 |
Document ID | / |
Family ID | 32588384 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040120230 |
Kind Code |
A1 |
Miyata, Yasuhisa ; et
al. |
June 24, 2004 |
Apparatus and method for adjusting optical pickup
Abstract
A light receiving unit 20A has a half mirror 20Aa and a
photoreceptor device 20Af. A signal processing member 20B generates
a focus error signal e from photoelectric conversion signals a, b,
c and d which are outputted from the light receiving unit 20A, and
further generates a focus error signal e1 from photoelectric
conversion signals a1, b1, c1 and d1 which are outputted from a
photoreceptor device 7 of an optical pickup P subject to
adjustment. A control member 20C performs attitude control on an
actuator 5A of an objective lens of the optical pickup P based on
the focus error signal e, and creates data for adjusting the
optical pickup P based on the focus error signal e1.
Inventors: |
Miyata, Yasuhisa;
(Saitama-ken, JP) ; Nakahashi, Masahiro;
(Saitama-ken, JP) |
Correspondence
Address: |
MCGINN & GIBB, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA
VA
22182-3817
US
|
Assignee: |
Pioneer Corporation
Tokyo
JP
Pioneer FA Corporation
Tsurugashima-shi
JP
|
Family ID: |
32588384 |
Appl. No.: |
10/732454 |
Filed: |
December 11, 2003 |
Current U.S.
Class: |
369/44.29 ;
G9B/7.061; G9B/7.138 |
Current CPC
Class: |
G11B 7/082 20130101;
G11B 7/22 20130101 |
Class at
Publication: |
369/044.29 |
International
Class: |
G11B 007/095 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2002 |
JP |
2002-369238 |
Claims
What is claimed is:
1. An apparatus for adjusting an optical pickup including a light
emission member, an objective lens provided for the directing of a
beam outputted from the light emission member, an actuator for
operating the objective lens, a multi lens for bringing the beam
reflected into focus, and a photoreceptor device for receiving the
beam reflected, the apparatus comprising: a light-receiving unit
having a half mirror member allowing a portion of the beam
outputted from the light emission member of the optical pickup
subject to adjustment to pass therethrough and reflecting a portion
of the beam toward the optical pickup, and an optical system
including a photoreceptor device receiving the beam passing through
the half mirror member; a signal processing member that fetches a
photoelectric conversion signal outputted from the photoreceptor
device of the light-receiving unit as a result of receiving the
beam, then generates from the photoelectric conversion signal a
first focus error signal representing an optical axis position and
a focal point of the beam entering the photoreceptor device of the
light-receiving unit, and that also fetches a photoelectric
conversion signal outputted from the photoreceptor device of the
optical pickup as a result of receiving the beam reflected off the
half mirror member, and then generates from the photoelectric
conversion signal a second focus error signal representing an
optical axis position and a focal point of the beam entering the
photoreceptor device of the optical pickup; and a control member
that operationally controls the actuator of the objective lens of
the optical pickup on the basis of the first focus error signal
supplied from the signal processing member, and generates
adjustment data used for making focus adjustment and optical axis
adjustment to the optical pickup on the basis of the second focus
error signal.
2. An apparatus for adjusting an optical pickup according to claim
1, wherein the half mirror member of said light-receiving unit is
constructed of a half mirror body and cover glasses of the same
material and the same thickness provided on both faces of the half
mirror body to sandwich the half mirror body.
3. An apparatus for adjusting an optical pickup according to claim
1, wherein the photoreceptor device of said light receiving unit
has a receiving surface divided into a plurality of areas, and
outputs, from the respective divided areas, the photoelectric
conversion signals of the beam received.
4. An apparatus for adjusting an optical pickup according to claim
3, wherein the receiving surface of the photoreceptor device of
said light receiving unit is equally divided into four areas by
straight lines intersecting at right angles at the center of the
receiving surface.
5. An apparatus for adjusting an optical pickup according to claim
1, wherein the photoreceptor device of said light receiving unit
has a receiving surface divided into a plurality of areas, and said
signal processing member generates the first focus error signal on
the basis of the photoelectric conversion signals, respectively
outputted from the divided areas of the receiving surface, by means
of calculating a difference in output between the photoelectric
conversion signals.
6. An apparatus for adjusting an optical pickup according to claim
1, wherein the photoreceptor device of the optical pickup has a
receiving surface divided into a plurality of areas, and said
signal processing member generates the second focus error signal on
the basis of the photoelectric conversion signals, respectively
outputted from the divided areas of the receiving surface, by means
of calculating a difference in output between the photoelectric
conversion signals
7. An apparatus for adjusting an optical pickup according to claim
1, wherein the adjustment data is data for moving a position of the
multi lens of the optical pickup and a position of the
photoreceptor device of the optical pickup.
8. An apparatus for adjusting an optical pickup according to claim
1, wherein said control member has a display and the adjustment
data is shown on the display.
9. An apparatus for adjusting an optical pickup according to claim
1, further comprising an adjusting member for adjusting positions
of the multi lens and the photoreceptor device of the optical
pickup, wherein said control member outputs the adjustment data to
the adjusting member to allow the adjusting member to make
adjustments to the optical pickup.
10. A method for adjusting an optical pickup including a light
emission member, an objective lens provided for the directing of a
beam outputted from the light emission member, an actuator for
operating the objective lens, a multi lens for bringing the beam
reflected into focus, and a photoreceptor device for receiving the
beam reflected, the method for adjusting the optical pickup
comprising the steps of: outputting the beam from the light
emission member of the optical pickup subject to adjustment in a
direction of a half mirror member allowing a portion of the beam to
pass therethrough and reflecting a portion of the beam; receiving
the beam passing through the half mirror member on a photoreceptor
device of an optical system having the same structure as that of
the optical pickup; generating a first focus error signal,
representing an optical-axis position and a focal point of the beam
entering the photoreceptor device of the optical system, on the
basis of a photoelectric conversion signal-outputted from the
photoreceptor device concerned as a result of receiving the beam;
controlling operation of the actuator of the objective lens of the
optical pickup on the basis of the first focus error signal, so
that the beam outputted from the light emission member of the
optical pickup and passing through the half mirror member is
focused on a receiving surface of the photoreceptor device of the
optical system and also an optical axis of the beam is aligned with
an optical axis of the receiving surface; receiving the beam,
reflected from the half mirror member, on the photoreceptor device
of the optical pickup subject to adjustment; generating a second
focus error signal, representing an optical-axis position and a
focal point of the beam entering the photoreceptor device of the
optical pickup, on the basis of a photoelectric conversion signal
outputted from the photoreceptor device of the optical pickup as a
result of receiving the beam; and generating adjustments data on
the basis of the second focus error signal for making positional
adjustment to the multi lens and the photoreceptor device of the
optical pickup, so that the beam outputted from the light emission
member of the optical pickup and reflected from the half mirror
member is focused on a receiving surface of the photoreceptor
device of the optical pickup and also an optical axis of the beam
is aligned with an optical axis of the receiving surface.
11. A method for adjusting an optical pickup according to claim 10,
wherein the half mirror member is structured by sandwiching a half
mirror body between cover glasses made of the same material as each
other and having the same thickness as each other.
12. A method for adjusting an optical pickup according to claim 10,
wherein the receiving surface of the photoreceptor device of the
light receiving unit is divided into a plurality of areas, and the
photoreceptor device outputs the photoelectric conversion signals
of the receiving beam from the respective divided areas.
13. A method for adjusting an optical pickup according to claim 12,
wherein the receiving surface of the photoreceptor device of the
light receiving unit is equally divided into the four areas by
straight lines intersecting at right angles at the center of the
receiving surface.
14. A method for adjusting an optical pickup according to claim 10,
wherein the receiving surface of the photoreceptor device of said
light receiving unit is divided into a plurality of areas, and
based on the photoelectric conversion signals respectively
outputted from the divided areas of the receiving surface, a
difference in output between the photoelectric conversion signals
is calculated to generate the first focus error signal.
15. A method for adjusting an optical pickup according to claim 10,
wherein the receiving surface of the photoreceptor device of the
optical pickup is divided into a plurality of areas, and said based
on the photoelectric conversion signals respectively outputted from
the divided areas of the receiving surface, a difference in output
between the photoelectric conversion signals is calculated to
generate the second focus error signal.
16. A method for adjusting an optical pickup according to claim 10,
wherein based on the second focus error signal, the adjustment data
is created for moving the position of the multi lens of the optical
pickup and the position of the photoreceptor device of the optical
pickup.
17. A method for adjusting an optical pickup according to claim 10,
wherein the adjustment data is shown on a display.
18. A method for adjusting an optical pickup according to claim 10,
wherein the adjustment data is supplied to an adjusting member for
adjusting the positions of the multi lens and the photoreceptor
device of the optical pickup to allow the adjusting member to make
adjustments to the optical pickup.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an apparatus and a method for
adjusting the optical system of an optical pickup provided for
reading information recorded in an optical disc and writing
information into the optical disc.
[0003] The present application claims priority from Japanese
Application No. 2002-369238, the disclosure of which is
incorporated herein by reference.
[0004] 2. Description of the Related Art
[0005] FIG. 1 is a perspective view schematically illustrating a
typical structure of an optical pickup used in a DVD player or DVD
recorder.
[0006] In FIG. 1, an optical pickup P is constituted of: a DVD
(Digital Versatile Disc) laser diode LD1 and a CD (Compact Disc)
laser diode LD2 for outputting beams at different wavelengths from
each other; half mirrors 1 and 2 and a mirror 3 for guiding an
output beam b1, emitted from the DVD laser diode LD1 or CD laser
diode LD2, along a predetermined path; a collimator lens 4 for
making the output beam b1 come in parallel light rays; an objective
lens 5 undergoing attitude control by an actuator to irradiate a
disc with the beam; a multi lens 6 for receiving a beam b2
reflected off the disc D and then passing through the objective
lens 5, collimator lens 4, mirror 3 and half mirror 2; and a
photoreceptor device 7, such as a photo-detector or an optical
electronics IC, for receiving the reflected beam b2 focused by the
multi lens 6, to read the information.
[0007] Prior to the process of mounting the optical pickup on a
player or recorder in the manufacturing process, the optical pickup
P undergoes: an attitude adjustment to the actuator actuating the
objective lens 5 by use of a beam spot adjuster (an output-path
optical-axis adjustment); a focus adjustment to the multi lens 6
and a positional adjustment to the photoreceptor device 7 by use of
an optical-path adjuster (a receptor optical axis adjustment); and
an optical-axis adjustment of the CD laser diode LD2 by use of the
optical-path adjuster after completion of the focus adjustment of
the multi lens 6 and the positional adjustment of the photoreceptor
device 7.
[0008] FIG. 2 is a schematic block diagram illustrating a
conventional optical path adjuster, and FIG. 3 is a diagram
illustrating an adjusting method using the conventional optical
path adjuster.
[0009] For the foregoing adjustments, the conventional optical path
adjuster 10 uses an optical pickup P to actually irradiate a disc D
with a beam. The optical path adjuster 10 includes a disc drive 10A
for rotationally driving the disc D used in the adjustment process;
a pickup control circuit 10B for executing the drive control of the
disc drive 10A and an operation control for an actuator 5A of an
objective lens 5 of the optical pickup P; a signal processing
circuit 10C for processing a disc signal detected by an
photoreceptor device 7 of the optical pickup P; a measurement
hardware 10D for analyzing the disc signal undergoing the signal
processing in the signal processing circuit 10C, and using a jitter
meter or an oscilloscope for analyzing the focus and the optical
axis position of the reflected beam b2 (see FIG. 1) entering the
photoreceptor device 7; and a main controller (e.g. personal
computer) 10E for making an assessment of the optical pickup
adjustment on the basis of the result of analysis made by the
measurement hardware 10D, and creating adjustment data.
[0010] The optical axis adjuster 10 adjusts the optical axis in the
optical pickup P by following the procedure as illustrated in the
flowchart in FIG. 4.
[0011] After the completion of attitude adjustment made to the
actuator 5A by use of the beam spot adjuster (the output-path
optical axis adjustment), the optical pickup P is placed in the
checking position of the optical axis adjuster 10, and connected to
a power supply circuit (not shown). Then the actuator 5A is
connected to the pickup control circuit 10B, and the photoreceptor
device 7 is connected to the signal processing circuit 10C.
[0012] At this point, the optical axis adjuster 10 starts rotating
the disc D, and starts the DVD laser diode LD1 emitting light (step
s1).
[0013] Upon the photoreceptor device 7 receiving a reflected beam
b2 from the disc D and outputting a disc signal, the signal
processing circuit 10C fetches the disc signal (step s2).
[0014] The signal processing circuit 10C performs the signal
processing on the disc signal fetched from the photoreceptor device
7, and generates therefrom a drive control signal for the disc
drive 10A and an attitude control signal for the actuator 5A (step
s3). Then, based on the drive control signal and the attitude
control signal, the pickup control circuit 10B performs the drive
control on the disc drive 10A and enables the actuator SA to
control the attitude of the objective lens 5 (step s4).
[0015] After the completion of the drive control for the disc drive
10A and the attitude control for the actuator 5A by the pickup
control circuit 10B, the photoreceptor device 7 receives the
reflected beam b2 and outputs a disc signal. Thereupon, the signal
processing circuit 10C performs measurement signal processing on
the disc signal (step s5).
[0016] Then, based on the disc signal undergoing the measurement
signal processing performed by the signal processing circuit 10C,
the measurement hardware 10D analyzes the focus and the optical
axis position of the reflected beam b2 entering the photoreceptor
device 7 (step s6).
[0017] The main controller 10E evaluates the high-frequency
characteristics and the like of the disc signal on the basis of the
result of the analysis made by the measurement hardware 10D, and
accordingly determines whether or not there is the need of optical
axis adjustment, namely, the need of focus adjustment to the multi
lens 6 and light-receiving point adjustment to the photoreceptor
device 7 (step s7).
[0018] If the main controller 10E determines the need of focus
adjustment to the multi lens 6 or light-receiving point adjustment
to the photoreceptor device 7 in step s7, then the main controller
10E generates data required for carrying out the adjustments (step
s8).
[0019] Next, when the optical pickup P is adjusted manually, based
on the adjustment data shown on the display of the main controller
10E, the operator slides the multi lens 6 of the optical pickup P
in the z-axis direction as illustrated in FIG. 1, and/or moves the
photoreceptor device 7 in the x-axis and y-axis directions as
illustrated in FIG. 1, and then fine-tunes the position of the
multi lens 6 or the photoreceptor device 7. Alternatively, when the
optical pickup P is adjusted by use of an automatic adjusting
device (not shown), the computer PC sends the adjustment data to
the automatic adjusting apparatus so that the multi lens 6 or the
photoreceptor device 7 is fine-tuned in position as in the case of
manual adjustment (step s9).
[0020] After the completion of focus adjustment to the multi lens 6
or light-receiving point adjustment to the photoreceptor device 7,
the procedure of the steps s2 to s9 is repeated until the main
controller 10E determines at step s7 that there is no need of focus
adjustment to the multi lens 6 or light-receiving point adjustment
to the photoreceptor device 7.
[0021] Then, when the main controller 10E determines at step s7
that there is no need of focus adjustment to the multi lens 6 or
light-receiving point adjustment to the photoreceptor device 7, the
adjustment process relating to the DVD laser diode LD1 of the
optical pickup P is terminated.
[0022] When the optical pickup P is further equipped with a CD
laser diode LD2 besides the DVD laser diode LD1 as described in
FIG. 1, an optical axis adjuster designed for a CD optical system
analyzes a disc signal outputted from the photoreceptor device 7 in
the same procedure as in the foregoing case of the DVD laser diode
LD1, and then, based on the analyzed result, the position of the CD
laser diode LD2 is adjusted.
[0023] Such the foregoing conventional apparatus and method for
adjusting optical pickup are showed in JP Pat. Publication No.
2002-133708.
[0024] As described hitherto, for adjustment to the optical pickup
P, a conventional optical pickup adjusting apparatus actually
applies an output beam b1 from the optical pickup P to the disc D,
and then detects the beam b2 reflected from the disc D. The reason
is as follows.
[0025] If the output beam b1 applied from the optical pickup is
reflected off a mirror instead of the disc, even when the output
beam 1 is not focused on the mirror (i.e. when it is impossible to
actually read the information on the disc), the reflected beam b2
may be focused on the photoreceptor device 7, resulting in the
impossibility to make a normal adjustment.
[0026] Because of this, an actual disc such as a DVD or a CD is
used for making adjustment to the optical pickup P. In this event,
however, the optical pickup adjusting apparatus is required to have
a disc drive mechanism, a drive circuit configured only for
executing various controls for tracking, auto-focusing and the like
appropriate to the optical pickup P subject to adjustment,
measurement hardware for analyzing a disc signal, and the like.
[0027] For this reason, in a conventional optical pickup adjusting
apparatus, whenever the model of optical pickup P changes, it is
necessary to make a change of drive circuit and control program.
Therefore, it costs both large amount of labor and expenses at the
time of beginning of new product introduction.
[0028] Further, a conventional optical pickup adjusting apparatus
structured as described above needs to perform the processes for
adjusting the focus of the multi lens 6, the position of the
photoreceptor device 7, and the position of the CD laser diode LD2
independently of the process for making the attitude adjustment to
the actuator operating the objective lens 5 by use of the beam spot
adjuster (the initial-output optical axis adjustment). Such
separation of processes causes the problems of complication in the
facilities for the optical pickup adjustment, and occurrences of
error in the adjusting processes.
SUMMARY OF THE INVENTION
[0029] The present invention has been made to solve the problems
associated with the conventional apparatus and method for adjusting
an optical pickup as described hitherto.
[0030] Accordingly, an object of the present invention is to
provide an apparatus and a method for adjusting an optical pickup
that enable reductions in effort and costs incurred when the
manufacturing of new products is launched, and also the prevention
of complications in the facilities for adjusting the optical pickup
and of occurrence of error in adjusting processes.
[0031] To achieve this object, in a first aspect, the present
invention provides an apparatus for adjusting an optical pickup
including: a light emission member; an objective lens provided for
the directing of a beam outputted from the light emission member;
an actuator for operating the objective lens; a multi lens for
bringing the beam reflected into focus; and a photoreceptor device
for receiving the beam reflected, and this apparatus has the
feature of including: a light-receiving unit having a half mirror
member allowing a portion of the beam outputted from the light
emission member of the optical pickup subject to adjustment to pass
therethrough, and reflecting a portion of the beam toward the
optical pickup, and an optical system including a photoreceptor
device receiving the beam passing through the half mirror member; a
signal processing member that fetches a photoelectric conversion
signal outputted from the photoreceptor device of the
light-receiving unit as a result of receiving the beam, then
generates from the photoelectric conversion signal a first focus
error signal representing an optical axis position and a focal
point of the beam entering the photoreceptor device of the
light-receiving unit, and that also fetches a photoelectric
conversion signal outputted from the photoreceptor device of the
optical pickup as a result of receiving the beam reflected off the
half mirror member, and then generates from the photoelectric
conversion signal a second focus error signal representing an
optical axis position and a focal point of the beam entering the
photoreceptor device of the optical pickup; and a control member
that operationally controls the actuator of the objective lens of
the optical pickup on the basis of the first focus error signal
supplied from the signal processing member, and generates
adjustment data used for making focus adjustment and optical axis
adjustment to the optical pickup on the basis of the second focus
error signal.
[0032] Regarding the optical pickup adjusting apparatus in the
first aspect of the present invention, an optical pickup subject to
adjustment is located in a predetermined position, and then a beam
is outputted from the light emission member of the optical pickup
toward the light receiving unit, thereby performing the attitude
control on the actuator operating the objective lens of the optical
pickup, the focus adjustment to the multi lens, and the optical
axis adjustment to the photoreceptor device.
[0033] Specifically, a portion of the beam outputted from the light
emission member of the optical pickup toward the light receiving
unit passes through the half mirror member of the light receiving
unit, and enters the photoreceptor device of the light receiving
unit, and then a photoelectric conversion signal is outputted from
the photoreceptor device to the signal processing member.
[0034] The signal processing member fetches the photoelectric
conversion signal outputted from the photoreceptor device of the
light receiving unit, and then generates a first focus error signal
representing the optical axis position and the focal point of the
beam entering the photoreceptor device of the light receiving
unit.
[0035] Then, based on the first focus error signal generated by the
signal processing member, the control member performs the attitude
control on the actuator operating the objective lens of the optical
pickup, so that the beam outputted from the optical pickup is
focused on the half mirror member and also the optical axis of the
beam is aligned with that of the photoreceptor device of the light
receiving unit.
[0036] On the other hand, the beam reflected from the half mirror
member of the light receiving unit enters the photoreceptor device
of the optical pickup. Then the photoreceptor device also outputs a
photoelectric conversion signal. The signal processing member
fetches the photoelectric conversion signal outputted from the
photoreceptor device of the optical pickup, and thus generates,
from the photoelectric conversion signal, a second focus error
signal representing the optical axis position and the focal point
of the beam entering the photoreceptor device of the optical
pickup.
[0037] Then the control member, after the completion of attitude
control on the actuator of the objective lens of the optical pickup
based on the first focus error signal, generates adjustment data
used for making the focus adjustment and the optical axis
adjustment to the optical pickup on the basis of the second focus
error signal.
[0038] Based on the adjustment data thus generated, the operator
manually adjusts, or alternatively an adjusting device
automatically adjusts the position of the multi lens of the optical
pickup for the focus adjustment, and adjusts the position of the
photoreceptor device of the optical pickup for the optical axis
adjustment.
[0039] As described hitherto, with the optical pickup adjusting
apparatus according to the present invention, without the use of a
disc, a light receiving unit having a structure similar to that of
an optical pickup subject to adjustment receives a beam outputted
from the optical pickup in order to adjust the optical axis. This
eliminates the need for a disc drive mechanism, a drive circuit
configured only for executing various controls for tracking,
auto-focusing and the like appropriate to the optical pickup
subject to adjustment, measurement hardware for analyzing a disc
signal, and the like, as are needed conventionally.
[0040] As a result, besides having this simplification in its
structure, the apparatus for adjusting the optical pickup according
to the present invention is capable of easily accommodating the
changing of models of the optical pickup, and therefore of offering
a significant reduction in effort and costs incurred when launching
the manufacturing of new products.
[0041] Further, the apparatus for adjusting the optical pickup
according to the present invention is capable by itself of
continuously carrying out the attitude adjustment to the actuator,
the focus adjustment to the multi lens and the attitude adjustment
to the photoreceptor device of the optical pickup. This makes it
possible to simplify the facilities for the optical-axis adjustment
to the optical pickup and also prevent the occurrence of errors in
the adjusting processes.
[0042] To achieve the aforementioned object, in a second aspect,
the present invention provides a method for adjusting an optical
pickup including: a light emission member; an objective lens
provided for the directing of a beam outputted from the light
emission member; an actuator for operating the objective lens; a
multi lens for bringing the beam reflected into focus; and a
photoreceptor device for receiving the beam reflected, and this
method of adjusting the optical pickup has the feature of including
the steps of: outputting the beam from the light emission member of
the optical pickup subject to adjustment in a direction of a half
mirror member allowing a portion of the beam to pass therethrough
and reflecting a portion of the beam; receiving the beam passing
through the half mirror member on a photoreceptor device of an
optical system having the same structure as that of the optical
pickup; generating a first focus error signal, representing an
optical-axis position and a focal point of the beam entering the
photoreceptor device of the optical system, on the basis of a
photoelectric conversion signal outputted from the photoreceptor
device of the optical system as a result of receiving the beam;
controlling operation of the actuator of the objective lens of the
optical pickup on the basis of the first focus error signal, so
that the beam outputted from the light emission member of the
optical pickup and passing through the half mirror member is
focused on a receiving surface of the photoreceptor device of the
optical system and also an optical axis of the beam is aligned with
an optical axis of the receiving surface; receiving the beam,
reflected from the half mirror member, on the photoreceptor device
of the optical pickup subject to adjustment; generating a second
focus error signal, representing an optical-axis position and a
focal point of the beam entering the photoreceptor device of the
optical pickup, on the basis of a photoelectric conversion signal
outputted from the photoreceptor device of the optical pickup as a
result of receiving the beam; and generating adjustment data on the
basis of the second focus error signal for making positional
adjustments to the multi lens and the photoreceptor device of the
optical pickup so that the beam outputted from the light emission
member of the optical pickup and reflected off the half mirror
member is focused on a receiving surface of the photoreceptor
device of the optical pickup and also an optical axis of the beam
is aligned with an optical axis of the receiving surface.
[0043] As regards the method of adjusting the optical pickup
according to the present invention, an optical pickup subject to
adjustment is placed in a predetermined position, and then a beam
is outputted from the light emission member of the optical pickup
toward a half mirror member. The half mirror member allows a
portion of the beam to pass therethrough and reflects a portion of
the beam.
[0044] The portion of the beam outputted from the light emission
member of the optical pickup, which passes through the half mirror
member, enters the photoreceptor device of the optical system
having the same structure as that of the optical pickup.
[0045] When the photoreceptor device of the optical system receives
the beam, the beam is photoelectrically converted. Thus the
photoreceptor device outputs a photoelectric conversion signal.
Based on the photoelectric conversion signal, a first focus error
signal representing the optical-axis position and the focal point
of the beam entering the photoreceptor device is generated.
[0046] Further, based on the first focus error signal, attitude
control is performed on the actuator operating the objective lens
of the optical pickup, so that the beam outputted from the light
emission member of the optical pickup and travelling through the
half mirror member focuses on the receiving surface of the
photoreceptor device of the optical system and the optical axis of
the beam is aligned with the optical axis of the receiving
surface.
[0047] On the other hand, the beam reflected off the half mirror
member enters the photoreceptor device of the optical pickup
subject to adjustment. The photoreceptor device of the optical
pickup receives the beam and thereupon outputs a photoelectric
conversion signal. Based on the photoelectric conversion signal, a
second focus error signal representing the optical-axis position
and the focal point of the beam entering the photoreceptor device
concerned is generated.
[0048] Further, data for making adjustments is created on the basis
of the second focus error signal. With this data, the positions of
the multi lens and the photoreceptor device of the optical pickup
are adjusted, so that the beam outputted from the light emission
member of the optical pickup and then reflected by the half mirror
member focuses on the receiving surface of the photoreceptor device
of the optical pickup, and its optical axis comes into alignment
with that of the receiving surface.
[0049] As described hitherto, the method of adjusting the optical
pickup according to the present invention achieves an optical-axis
adjustment without the use of a disc. This eliminates the need for
a disc drive mechanism, a drive circuit configured only for
executing various controls for tracking, auto-focusing and the like
appropriate to the optical pickup subject to adjustment,
measurement hardware for analyzing a disc signal, and the like, as
are needed conventionally.
[0050] As a result, it is possible to make the optical-axis
adjustment to the optical pickup by use of an apparatus of a simple
structure, and thus to accommodate the changing of models of the
optical pickup, thereby significantly reducing the effort and costs
incurred when launching the manufacturing of new products.
[0051] Further, the method for adjusting the optical pickup
according to the present invention achieves the combination of the
attitude adjusting process for the actuator, the focus adjusting
process for the multi lens and the attitude adjusting process for
the photoreceptor device of the optical pickup. This makes it
possible to simplifies the facilities for making the optical-axis
adjustment to the optical pickup and also prevent the occurrence of
errors in the adjusting processes.
[0052] These and other objects and features of the present
invention will become more apparent from the following detailed
description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a perspective view schematically illustrating the
structure of an optical pickup.
[0054] FIG. 2 is a block diagram of a conventional optical axis
adjuster.
[0055] FIG. 3 is a more detailed block diagram illustrating the
conventional optical axis adjuster.
[0056] FIG. 4 is a flow chart illustrating the steps of a
conventional optical axis adjustment.
[0057] FIG. 5 is a block diagram illustrating an optical-pickup
adjusting apparatus according to the present invention.
[0058] FIG. 6 is a more detailed block diagram illustrating the
optical-pickup adjusting apparatus.
[0059] FIG. 7 is a side view illustrating the structure of a half
mirror in the optical-pickup adjusting apparatus.
[0060] FIG. 8 is a flow chart illustrating the steps of an optical
pickup adjustment performed by the optical-pickup adjusting
apparatus.
[0061] FIGS. 9A, 9B and 9C are diagrams for illustrating the
principle of focus adjusting in the optical-pickup adjusting
apparatus.
[0062] FIG. 10 is a diagram for illustrating the principle of
optical-axis adjusting in the optical-pickup adjusting
apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0063] A preferred embodiment according to the present invention
will be described below in detail with reference to the
accompanying drawings.
[0064] FIGS. 5 and 6 are block diagrams illustrating an embodiment
of an apparatus for adjusting an optical pickup (referred to as
"optical-pickup adjusting apparatus") according to the present
invention.
[0065] In FIGS. 5 and 6, an optical-pickup adjusting apparatus 20
includes: a light receiving unit 20A for receiving an output beam
b1 from the optical pickup P; a signal processing circuit 20B for
processing a photoelectric conversion signal outputted from the
light receiving unit 20A and a photoelectric conversion signal
outputted from the photoreceptor device 7 of the optical pickup P;
and a main controller (personal computer) 20C performing an
attitude control on the actuator 5A of the optical pickup P on the
basis of a focus error signal processed by the signal processing
circuit 20B, and determining the need for adjustments to the
optical pickup, and further creating data for performing the
adjustments.
[0066] The light receiving unit 20A in turn includes a half mirror
20Aa placed in a position receiving the output beam b1 from the
objective lens 5 of the optical pickup P (see FIG. 1), and an
objective lens 20Ab, a mirror 20Ac, a collimator lens 20Ad, a multi
lens 20Ae and a photoreceptor device 20Af which form an optical
system similar to the optical system of the optical pickup P.
[0067] As enlargedly illustrated in FIG. 7, the half mirror 20Aa of
the light receiving unit 20A is structured by sandwiching a half
mirror body 20Aa1 between cover glasses 20Aa2 of the same material
and the same thickness.
[0068] The multi lens 20Ae and the photoreceptor device 20Af of the
light receiving unit 20A are each adjusted such that a through beam
b3 passing through the half mirror 20Aa focuses on the
photoreceptor device 20Af when the output beam b1 travelling from
the optical pickup P toward the light receiving unit 20A focuses on
the half mirror 20Aa.
[0069] Next, a description will be given of the procedure of the
optical axis adjustment made to the optical pickup P by the optical
pickup adjusting apparatus 20.
[0070] The optical pickup P subject to the optical axis adjustment
is loaded in a checking position in the optical pickup adjusting
apparatus 20, and is connected to a power supply circuit (not
shown) Then, the photoreceptor device 7 is connected to the signal
processing circuit 20B, and the actuator 5A is connected to the
main controller 20C.
[0071] In this situation, the DVD laser diode LD1 of the optical
pickup P is actuated to emit light. The output beam b1 emitted from
the DVD laser diode LD1 enters the light receiving unit 20A (step
S1).
[0072] Approximately half the quantity of the output beam b1
entering the light receiving unit 20A passes through the half
mirror 20Aa and forms a through beam b3. The through beam b3
travels through the objective lens 20Ab, mirror 20Ac, collimator
lens 20Ad and multi lens 20Ae to enter the photoreceptor device
20Af. At this point, the half mirror 20Aa is located in a position
corresponding to the position of an actual disc. Hence, the through
beam b3 passes through the half mirror 20Aa under the same
conditions as in the case where the through beam b3 is reflected
off the disc, which will be described later.
[0073] Upon reception of the through beam b3, the photoreceptor
device 20Af of the light receiving unit 20A supplies photoelectric
conversion signals a, b, c and d to the signal processing circuit
20B. The photoelectric conversion signals a, b, c and d represent
the respective quantities of light received in divided screens of
the photoreceptor device 20Af, which will be described later (step
S2).
[0074] The signal processing circuit 20B processes the
photoelectric conversion signals a, b, c and d supplied from the
light receiving unit 20A to generate a focus error signal e on the
basis of the following principle (step S3).
[0075] As illustrated in FIG. 9, the photoreceptor device 20Af has
the receiving surface 20Af1 divided into quarter screens A, B, C
and D. The photoelectric conversion signals a, b, c and d
corresponding to the quantities of light received on the divided
screens A, B, C and D are applied to the signal processing circuit
20B.
[0076] Then, the signal processing circuit 20B generates the focus
error signal e from the photoelectric conversion signals a, b, c
and d, supplied from the photoreceptor device 20Af of the light
receiving unit 20A, on the basis of the following operational
expression.
e=(a+c)-(b+d)
[0077] FIG. 9A illustrates when the through beam b3 passing through
the half mirror 20Aa focuses on the photoreceptor device 20Af of
the light receiving unit 20A (i.e. focused on the half mirror
20Aa). In this event, the outputs of the photoelectric conversion
signals a, b, c and d are equal to each other. Therefore, based on
the foregoing expression, the focus error signal e is outputted at
zero from the signal processing circuit 20B.
[0078] FIG. 9B illustrates when the through beam b3 focuses at a
point this side of the photoreceptor device 20Af of the light
receiving unit 20A (i.e. focused at a point this side of the half
mirror 20Aa). In this event, the outputs of the photoelectric
conversion signals a, b, c and d are different from each other.
Therefore, based on the foregoing expression, a positive focus
error signal e is outputted from the signal processing circuit
20B.
[0079] FIG. 9C illustrates when the through beam b3 focuses at a
point beyond the photoreceptor device 20Af of the light receiving
unit 20A (i.e. focused at a point beyond the half mirror 20Aa) . In
this event, the outputs of the photoelectric conversion signals a,
b, c and d are different from each other. Therefore, based on the
foregoing expression, a negative focus error signal e is outputted
from the signal processing circuit 20B.
[0080] FIG. 10 illustrates when the optical axis of the through
beam b3 is out of alignment with the center of the photoreceptor
device 20Af of the light receiving unit 20A. In this event,
different focus error signals e in accordance with the amount and
the direction of deviation of the optical axis of the through beam
b3 are supplied from the signal processing circuit 20B to the main
controller 20C.
[0081] The main controller 20C performs attitude control on the
actuator 5A of the optical pickup P on the basis of the focus error
signal e supplied from the signal processing circuit 20B. Hence, an
adjustment is made to enable the beam b3 to focus on the
photoreceptor device 20Af of the light receiving unit 20A (i.e. on
the half mirror 20Aa), and the optical axis of the beam b3 to be
aligned with the center of the photoreceptor device 20Af (step
S4).
[0082] On the other hand, another portion of the output beam b1 of
the optical pickup P is reflected off the half mirror 20Aa toward
the optical pickup P to form a reflected beam b2. The reflected
beam b2 travels through the multi lens 6 to enter the photoreceptor
device 7. Thus, photoelectric conversion signals a1, b1, c1 and d1,
representing the amounts of light respectively received on the four
divided screens of the photoreceptor device 7 as in the case of the
photoreceptor device 20Af, are outputted from the photoreceptor
device 7 to the signal processing circuit 20B (step S5).
[0083] The reflected beam b2 reflected by the half mirror 20Aa is
equivalent in characteristics to the through beam b3 which passes
through the cover glasses 20Aa2 of the same material and thickness
provided on the both faces of the half mirror 20Aa in order to
travel through the half mirror 20Aa toward the photoreceptor device
20Af.
[0084] In the same manner of processing as with the photoelectric
conversion signals a, b, c and d supplied from the light receiving
unit 20A, the signal processing circuit 20B performs the signal
processing based on the photoelectric conversion signals a1, b1, c1
and d1 supplied from the photoreceptor device 7 to generate a focus
error signal e1 (step S6).
[0085] Then, after completion of the attitude adjustment of the
actuator 5A of the optical pickup P, the main controller 20C
determines, based on the focus error signal e1 supplied from the
signal processing circuit 20B, whether or not there is need for an
optical axis adjustment, namely, need for a focus adjustment to the
multi lens 6 and a light-receiving point adjustment to the
photoreceptor device 7 (step S7).
[0086] If the output of the focus error signal e1 is not zero at
step S7, the main controller 20C generates adjustment data for
adjusting the focus of the multi lens 6 and the light-receiving
point of the photoreceptor device 7 in accordance with the
magnitude of the output of the focus error signal e1 (step S8).
[0087] When the adjustment is made to the optical pickup P by hand,
based on the adjustment data shown on the display of the main
controller 20C, the operator slides the multi lens 6 of the optical
pickup P in the z direction and/or moves the photoreceptor device 7
in the x-axis and y-axis directions for fine-tuning (see FIG. 1).
Alternatively, when the optical pickup P is adjusted by use of an
automatic adjusting device (not shown), the main computer 20C sends
the adjustment data to the automatic adjusting apparatus so that
the position of the multi lens 6 or the photoreceptor device 7 is
fine-tuned as in the case of manual adjustment (step S9).
[0088] After the completion of focus adjustment to the multi lens 6
or light-receiving point adjustment to the photoreceptor device 7,
the procedure of the steps S5 to S9 is repeated until the main
controller 20C determines at step S7 that there is no need for
focus adjustment to the multi lens 6 or light-receiving point
adjustment to the photoreceptor device 7.
[0089] Then, if the main controller 20C determines at step S7 that
there is no need for focus adjustment to the multi lens 6 or
light-receiving point adjustment to the photoreceptor device 7, the
adjustment process relating to the DVD laser diode LD1 of the
optical pickup P is terminated.
[0090] When the optical pickup P is further equipped with a CD
laser diode LD2 besides the DVD laser diode LD1 as described in
FIG. 1, the DVD laser diode LD1 is caused to emit light, and then
by use a similar procedure as described above, positional
adjustment for the CD laser diode DL2 is performed (see FIG.
1).
[0091] As described hitherto, with the optical pickup adjusting
apparatus 20, without the use of a disc, the light receiving unit
20A, preset and having a structure similar to that of an optical
pickup subject to adjustment, receives a output beam b1 travelling
from the optical pickup P in order to adjust the optical axis. This
eliminates the need for a disc drive mechanism, a drive circuit
configured only for executing various controls for tracking,
auto-focusing and the like appropriate to the optical pickup
subject to adjustment, measurement hardware for analyzing a disc
signal, and the like, as are needed conventionally.
[0092] As a result, besides having this simplification in its
structure, the optical-pickup adjusting apparatus of the present
invention is capable of easily accommodating the changing of models
of the optical pickup, and therefore of achieving a significant
reduction in the effort and costs incurred when launching the
manufacturing of new products.
[0093] Further, the optical-pickup adjusting apparatus 20 is
capable by itself of continuously carrying out the beam spot
adjustment making attitude adjustment (an initial-output optical
axis adjustment) to the actuator 5A of the optical pickup P, the
focus adjustment to the multi lens 6, the position adjustment to
the photoreceptor device 7, and the positional adjustment for the
CD laser diode LD2. This makes it possible to simplify the
facilities for making optical-axis adjustment to the optical
pickup, and also to prevent the occurrence of errors in the
adjusting processes.
[0094] A generic concept of the optical-pickup adjusting apparatus
described in the foregoing embodiment is embodied in an apparatus
for adjusting an optical pickup including: a light emission member;
an objective lens provided for the directing of a beam outputted
from the light emission member; an actuator for operating the
objective lens; a multi lens for bringing the beam reflected into
focus; and a photoreceptor device for receiving the beam reflected,
and this apparatus includes: a light-receiving unit having a half
mirror member allowing a portion of the beam outputted from the
light emission member of the optical pickup subject to adjustment
to pass therethrough, and reflecting a portion of the beam toward
the optical pickup, and an optical system including a photoreceptor
device receiving the beam passing through the half mirror member; a
signal processing member that fetches a photoelectric conversion
signal outputted from the photoreceptor device of the
light-receiving unit as a result of receiving the beam, then
generates from the photoelectric conversion signal a first focus
error signal representing an optical axis position and a focal
point of the beam entering the photoreceptor device of the
light-receiving unit, and that also fetches a photoelectric
conversion signal outputted from the photoreceptor device of the
optical pickup as a result of receiving the beam reflected off the
half mirror member, and then generates from the photoelectric
conversion signal a second focus error signal representing an
optical axis position and a focal point of the beam entering the
photoreceptor device of the optical pickup; and a control member
that operationally controls the actuator of the objective lens of
the optical pickup on the basis of the first focus error signal
supplied from the signal processing member, and generates
adjustment data used for making focus adjustment and optical axis
adjustment to the optical pickup on the basis of the second focus
error signal.
[0095] In the optical pickup adjusting apparatus according to the
generic concept, an optical pickup subject to adjustment is loaded
in a predetermined position, and then a beam is outputted from the
light emission member of the optical pickup toward the light
receiving unit, thereby performing attitude control on the actuator
of the objective lens of the optical pickup, focus adjustment to
the multi lens, and optical axis adjustment to the photoreceptor
device.
[0096] A portion of the beam outputted from the light emission
member of the optical pickup in the direction of the light
receiving unit passes through the half mirror member of the light
receiving unit, and enters the photoreceptor device of the light
receiving unit, and then a photoelectric conversion signal is
outputted from the photoreceptor device to the signal processing
member.
[0097] The signal processing member fetches the photoelectric
conversion signal outputted from the photoreceptor device of the
light receiving unit, and then generates a first focus error signal
representing the optical axis position and the focal point of the
beam entering the photoreceptor device of the light receiving
unit.
[0098] Then, based on the first focus error signal generated by the
signal processing member, the control member performs attitude
control on the actuator of the objective lens of the optical
pickup, so that the beam outputted from the optical pickup is
focused on the half mirror member and also its optical axis is
aligned with the axis of the photoreceptor device of the light
receiving unit.
[0099] On the other hand, the beam reflected from the half mirror
member of the light receiving unit enters the photoreceptor device
of the optical pickup. Then the photoreceptor device also outputs a
photoelectric conversion signal. The signal processing member
fetches the photoelectric conversion signal outputted from the
photoreceptor device of the optical pickup, and thus generates, on
the basis of the photoelectric conversion signal, a second focus
error signal representing the optical axis position and the focal
point of the beam entering the photoreceptor device of the optical
pickup.
[0100] Then, the control member, after completing the attitude
control on the actuator of the objective lens of the optical pickup
based on the first focus error signal, generates adjustment data
used for making focus adjustment and optical axis adjustment to the
optical pickup on the basis of the second focus error signal.
[0101] Based on the adjustment data thus generated, the operator
manually adjusts, or alternatively an adjusting device
automatically adjusts, the position of the multi lens of the
optical pickup for the focus adjustment, and adjusts the position
of the photoreceptor device of the optical pickup for the optical
axis adjustment.
[0102] With the optical pickup adjusting apparatus as described
hitherto, without the use of a disc, a light receiving unit having
a structure similar to that of an optical pickup subject to
adjustment receives a beam outputted from the optical pickup in
order to adjust the optical axis. This eliminates the need for a
disc drive mechanism, a drive circuit configured only for executing
various controls for tracking, auto-focusing and the like
appropriate to the optical pickup subject to adjustment,
measurement hardware for analyzing a disc signal, and the like, as
are needed conventionally.
[0103] As a result, besides having this simplification in its
structure, the apparatus for adjusting the optical pickup is
capable of easily accommodating the changing of models of the
optical pickup, and therefore of offering a significant reduction
in the effort and costs incurred when launching the manufacturing
of new products.
[0104] Further, the apparatus for adjusting the optical pickup
according to the present invention is capable by itself of
continuously carrying out the attitude adjustment to the actuator,
the focus adjustment to the multi lens and the attitude adjustment
to the photoreceptor device of the optical pickup. This makes it
possible to simplify the facilities for making the optical-axis
adjustment to the optical pickup and also prevent the occurrence of
errors in the adjusting processes.
[0105] A generic concept of the optical-pickup adjusting method of
the aforementioned embodiment is embodied in a method for adjusting
an optical pickup including a light emission member; an objective
lens provided for the directing of a beam outputted from the light
emission member; an actuator for operating the objective lens; a
multi lens for bringing the beam reflected into focus; and a
photoreceptor device for receiving the beam reflected. This method
of adjusting the optical pickup has the feature of including the
steps of: outputting the beam from the light emission member of the
optical pickup subject to adjustment in a direction of a half
mirror member allowing a portion of the beam to pass therethrough
and reflecting a portion of the beam; receiving the beam passing
through the half mirror member on a photoreceptor device of an
optical system having the same structure as that of the optical
pickup; generating a first focus error signal, representing an
optical-axis position and a focal point of the beam entering the
photoreceptor device of the optical system, on the basis of a
photoelectric conversion signal outputted from the photoreceptor
device concerned as a result of receiving the beam; controlling
operation of the actuator of the objective lens of the optical
pickup on the basis of the first focus error signal, so that the
beam outputted from the light emission member of the optical pickup
and passing through the half mirror member is focused on a
receiving surface of the photoreceptor device of the optical system
and an optical axis of the beam is aligned with the optical axis of
the receiving surface; receiving the beam, reflected from the half
mirror member, on the photoreceptor device of the optical pickup
subject to adjustment; generating a second focus error signal
representing an optical-axis position and a focal point of the beam
entering the photoreceptor device of the optical pickup on the
basis of a photoelectric conversion signal outputted from the
photoreceptor device of the optical pickup as a result of receiving
the beam; and generating adjustment data on the basis of the second
focus error signal for making positional adjustment to the multi
lens and the photoreceptor device of the optical pickup, so that
the beam outputted from the light emission member of the optical
pickup and reflected from the half mirror member is focused on a
receiving surface of the photoreceptor device of the optical pickup
and also an optical axis of the beam is aligned with an optical
axis of the receiving surface.
[0106] In the method of adjusting the optical pickup according to
the generic concept, an optical pickup subject to adjustment is
placed in a predetermined position, and then a beam is outputted
from the light emission member of the optical pickup in the
direction of a half mirror member. The half mirror member allows a
portion of the beam to pass therethrough and reflects a portion of
the beam.
[0107] The portion of the beam outputted from the light emission
member of the optical pickup, which passes through the half mirror
member, enters the photoreceptor device of the optical system
having the same structure as that of the optical pickup.
[0108] When the photoreceptor device of the optical system receives
the beam, the beam is photoelectrically converted. Thus the
photoreceptor device outputs a photoelectric conversion signal.
Based on the photoelectric conversion signal, a first focus error
signal representing the optical-axis position and the focal point
of the beam entering the photoreceptor device is generated.
[0109] Further, based on the first focus error signal, attitude
control is performed on the actuator of the objective lens of the
optical pickup, so that the beam outputted from the light emission
member of the optical pickup and travelling through the half mirror
member focuses on the receiving surface of the photoreceptor device
of the optical system and the optical axis of the beam is aligned
with the optical axis of the receiving surface.
[0110] On the other hand, the beam reflected from the half mirror
member enters the photoreceptor device of the optical pickup
subject to adjustment. The photoreceptor device of the optical
pickup receives the beam and thereupon outputs a photoelectric
conversion signal. Based on the photoelectric conversion signal, a
second focus error signal representing the optical-axis position
and the focal point of the beam entering the photoreceptor device
concerned is generated.
[0111] Further, data for adjustments is created on the basis of the
second focus error signal. With this data, the positions of the
multi lens and the photoreceptor device of the optical pickup are
adjusted, so that the beam outputted from the light emission member
of the optical pickup and then reflected by the half mirror member
is focused on the receiving surface of the photoreceptor device of
the optical pickup, and also its optical axis is aligned with the
optical axis of the receiving surface.
[0112] The method of adjusting the optical pickup as described
hitherto achieves an optical-axis adjustment without the use of a
disc. This eliminates the need for a disc drive mechanism, a drive
circuit configured only for executing various controls for
tracking, auto-focusing and the like appropriate to the optical
pickup subject to adjustment, measurement hardware for analyzing a
disc signal, and the like, as are needed conventionally.
[0113] As a result, it is possible to make the optical-axis
adjustment to the optical pickup by use of an apparatus of a simple
structure, and thus to accommodate the changing of models of the
optical pickup, thereby significantly reducing the effort and costs
incurred when launching the manufacturing of new products.
[0114] Further, the method for adjusting the optical pickup
according to the present invention achieves the combination of the
attitude adjusting process for the actuator, the focus adjusting
process for the multi lens and the attitude adjusting process for
the photoreceptor device of the optical pickup. This makes it
possible to simplify the facilities for making the optical-axis
adjustment to the optical pickup and also prevent the occurrence of
errors in the adjusting processes.
[0115] The terms and description used herein are set forth by way
of illustration only and are not meant as limitations. Those
skilled in the art will recognize that numerous variations are
possible within the spirit and scope of the invention as defined in
the following claims.
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